Saturn S-2, S-4B, and instrument unit subassembly and assembly vibration and acoustic evaluation programs
Saturn S-2, S-4B, and instrument unit subassembly and assembly vibration and acoustic evaluation programs
Everitt, J. M.↗
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Space telescope optical telescope assembly/scientific instruments. Phase B: -Preliminary design and program definition study; Volume 2A: Planetary camera report
Development of the F/48, F/96 Planetary Camera for the Large Space Telescope is discussed. Instrument characteristics, optical design, and CCD camera submodule thermal design are considered along with structural subsystem and thermal control subsystem. Weight, electrical subsystem, and support equipment requirements are also included.
Source record↗
Research instrumentation for hot section components of turbine engines
Programs to develop research instrumentation for use on hot section components of turbine engines are discussed. These programs can be separated into two categories: one category includes instruments which can measure the environment within the combustor and turbine components, the other includes instruments which measure the response of engine components to the imposed environment. Included in the first category are instruments to measure total heat flux and fluctuating gas temperature. High temperature strain measuring systems, thin film sensors (e.g., turbine blade thermocouples) and a system to view the interior of a combustor during engine operation are programs which comprise the second category. The paper will describe the state of development of these sensors and measuring systems and, in some cases, show examples of measurements made with this instrumentation. The discussion will cover work done at NASA Lewis and at various contractor facilities.
Englund, D. R.↗
Automated Instrumentation, Monitoring and Visualization of PVM Programs Using AIMS
We present views and analysis of the execution of several PVM (Parallel Virtual Machine) codes for Computational Fluid Dynamics on a networks of Sparcstations, including: (1) NAS Parallel Benchmarks CG and MG; (2) a multi-partitioning algorithm for NAS Parallel Benchmark SP; and (3) an overset grid flowsolver. These views and analysis were obtained using our Automated Instrumentation and Monitoring System (AIMS) version 3.0, a toolkit for debugging the performance of PVM programs. We will describe the architecture, operation and application of AIMS. The AIMS toolkit contains: (1) Xinstrument, which can automatically instrument various computational and communication constructs in message-passing parallel programs; (2) Monitor, a library of runtime trace-collection routines; (3) VK (Visual Kernel), an execution-animation tool with source-code clickback; and (4) Tally, a tool for statistical analysis of execution profiles. Currently, Xinstrument can handle C and Fortran 77 programs using PVM 3.2.x; Monitor has been implemented and tested on Sun 4 systems running SunOS 4.1.2; and VK uses XIIR5 and Motif 1.2. Data and views obtained using AIMS clearly illustrate several characteristic features of executing parallel programs on networked workstations: (1) the impact of long message latencies; (2) the impact of multiprogramming overheads and associated load imbalance; (3) cache and virtual-memory effects; and (4) significant skews between workstation clocks. Interestingly, AIMS can compensate for constant skew (zero drift) by calibrating the skew between a parent and its spawned children. In addition, AIMS' skew-compensation algorithm can adjust timestamps in a way that eliminates physically impossible communications (e.g., messages going backwards in time). Our current efforts are directed toward creating new views to explain the observed performance of PVM programs. Some of the features planned for the near future include: (1) ConfigView, showing the physical topology of the virtual machine, inferred using specially formatted IP (Internet Protocol) packets: and (2) LoadView, synchronous animation of PVM-program execution and resource-utilization patterns.
Mehra, Pankaj↗
Feedback-Driven Dynamic Invariant Discovery
Program invariants can help software developers identify program properties that must be preserved as the software evolves, however, formulating correct invariants can be challenging. In this work, we introduce iDiscovery, a technique which leverages symbolic execution to improve the quality of dynamically discovered invariants computed by Daikon. Candidate invariants generated by Daikon are synthesized into assertions and instrumented onto the program. The instrumented code is executed symbolically to generate new test cases that are fed back to Daikon to help further re ne the set of candidate invariants. This feedback loop is executed until a x-point is reached. To mitigate the cost of symbolic execution, we present optimizations to prune the symbolic state space and to reduce the complexity of the generated path conditions. We also leverage recent advances in constraint solution reuse techniques to avoid computing results for the same constraints across iterations. Experimental results show that iDiscovery converges to a set of higher quality invariants compared to the initial set of candidate invariants in a small number of iterations.
Daikon↗
Automated Instrumentation, Monitoring and Visualization of PVM Programs Using AIMS
We present views and analysis of the execution of several PVM codes for Computational Fluid Dynamics on a network of Sparcstations, including (a) NAS Parallel benchmarks CG and MG (White, Alund and Sunderam 1993); (b) a multi-partitioning algorithm for NAS Parallel Benchmark SP (Wijngaart 1993); and (c) an overset grid flowsolver (Smith 1993). These views and analysis were obtained using our Automated Instrumentation and Monitoring System (AIMS) version 3.0, a toolkit for debugging the performance of PVM programs. We will describe the architecture, operation and application of AIMS. The AIMS toolkit contains (a) Xinstrument, which can automatically instrument various computational and communication constructs in message-passing parallel programs; (b) Monitor, a library of run-time trace-collection routines; (c) VK (Visual Kernel), an execution-animation tool with source-code clickback; and (d) Tally, a tool for statistical analysis of execution profiles. Currently, Xinstrument can handle C and Fortran77 programs using PVM 3.2.x; Monitor has been implemented and tested on Sun 4 systems running SunOS 4.1.2; and VK uses X11R5 and Motif 1.2. Data and views obtained using AIMS clearly illustrate several characteristic features of executing parallel programs on networked workstations: (a) the impact of long message latencies; (b) the impact of multiprogramming overheads and associated load imbalance; (c) cache and virtual-memory effects; and (4significant skews between workstation clocks. Interestingly, AIMS can compensate for constant skew (zero drift) by calibrating the skew between a parent and its spawned children. In addition, AIMS' skew-compensation algorithm can adjust timestamps in a way that eliminates physically impossible communications (e.g., messages going backwards in time). Our current efforts are directed toward creating new views to explain the observed performance of PVM programs. Some of the features planned for the near future include: (a) ConfigView, showing the physical topology of the virtual machine, inferred using specially formatted IP (Internet Protocol) packets; and (b) LoadView, synchronous animation of PVM-program execution and resource-utilization patterns.
Mehra, Pankaj↗
Progress of the Langley Research Center vacuum measurement program
Gauges and instrument calibration for vacuum measurement
MEASURING APPARATUS↗
Techniques for measuring stresses in rock on the earth - Adaptability to a lunar exploration program
Techniques and instrument developments for stress measurements in rocks on earth and moon
Goodman, R. E.↗
Lightning strike experience in the NASA F-106B storm hazards program
A heavily instrumented F-106B aircraft was flown in thunderstorms to gather data for characterizing lightning at aircraft operating altitudes. Conventional weather finding techniques are supplemented with UHF lightning mapping radar to select the most active storm cells and the most likely altitude for obtaining direct lightning strikes to the airplane. One hundred seventy-six strikes were obtained in a 3 year period, mostly at an altitude of above 25,000 feet.
Norman L Crabill↗
Investigation of the diffuse ultraviolet background using satellite data: Dynamics explorer guest investigator program
The imaging instrumentation for the Dynamics Explorer Mission was designed primarily to obtain global auroral images. The instrument, however, was also used successfully to study marine bioluminescence, the geocorona, and the global distribution of atmospheric ozone. The imager has considerable potential for the study of astronomical sources of ultraviolet radiation as well. The data produced by the imager is used to study the brightness and isotrophy of the diffuse ultraviolet background.
Fix, J. D.↗
MOD: An Instrument for the 2005 Mars Explorer Program HEDS Payload
The Mars Organic Detector (MOD) was recently selected for the definition phase of the HEDS '05 (originally scheduled for '03) lander instrument package for fundamental biology and in situ resource utilization. MOD is designed to detect organic compounds in rock and soil samples directly on the surface of Mars in order to assess the biological potential of the planet. In addition, a MOD Tunable Diode Laser Spectrometer (TDLS) will provide information on desorption and decomposition temperatures, as well as the release rates and quantities of water and carbon dioxide that can be liberated from regolith samples, thereby providing the parameters needed for the design of systems for the future large-scale in situ extraction of valuable consumable resources. A MOD TDLS will also measure the atmospheric water and carbon dioxide content, as well as the atmospheric carbon dioxide isotopic composition, in order to determine whether there is an isotopic offset between atmospheric and surface carbon.
Bada, J. L.↗
The NASA Thunderstorm Overflight Program (TOP): Research in atmospheric electricity from an instrumented U-2 aircraft platform
An overview of the NASA Thunderstorm Overflight Program (TOP) is presented. The various instruments flown on the NASA U-2 aircraft, as well as the ground instrumentation used to collect optical and electronic signature from the lightning events, are discussed. Samples of some of the photographic and electronic signatures are presented. Approximately 6400 electronic data samples of optical pulses were collected and are being analyzed.
Vaughan, O. H., Jr.↗
First planetary parachute test planned August 29
High altitude flight test of parachute design for landing instrumented capsules in Voyager program
FLIGHT TEST↗
Astrobiology Sample Analysis Program (ASAP) for Advanced Life Detection Instrumentation Development and Calibration
Scientific ground-truth measurements for near-term Mars missions, such as the 2009 Mars Science Laboratory (MSL) mission, are essential for validating current in situ flight instrumentation and for the development of advanced instrumentation technologies for life-detection missions over the next decade. The NASA Astrobiology Institute (NAI) has recently funded a consortium of researchers called the Astrobiology Sample Analysis Program (ASAP) to analyze an identical set of homogenized martian analog materials in a "round-robin" style using both state-of-the-art laboratory techniques as well as in-situ flight instrumentation including the SAM gas chromatograph mass spectrometer and CHEMIN X-ray diffraction/fluorescence instruments on MSL and the Urey and MOMA organic analyzer instruments under development for the 2013 ExoMars missions. The analog samples studied included an Atacama Desert soil from Chile, the Murchison meteorite, a gypsum sample from the 2007 AMASE Mars analog site, jarosite from Panoche Valley, CA, a hydrothermal sample from Rio Tinto, Spain, and a "blind" sample collected during the 2007 MSL slow-motion field test in New Mexico. Each sample was distributed to the team for analysis to: (1) determine the nature and inventory of organic compounds, (2) measure the bulk carbon and nitrogen isotopic composition, (3) investigate elemental abundances, mineralogy and matrix, and (4) search for biological activity. The experimental results obtained from the ASAP Mars analog research consortium will be used to build a framework for understanding the biogeochemistry of martian analogs, help calibrate current spaceflight instrumentation, and enhance the scientific return from upcoming missions.
Glavin, Daniel↗
Integrated display of multi-sensor geophysical and electromagnetic flight data
Low-altitude wind shear has been identified by several aviation interests as a significant hazard to the safety of flying. The hazard may be greatest when the wind shear is due to an unpredicted and short-lived microburst occurring in the immediate flight path of an aircraft during takeoff or landing. Researchers from the NASA Langley Research Center have investigated wind shear by developing a suite of remote sensing instruments and then using these instruments in an airborne wind shear detection flight program. Among these instruments were a Doppler radar, a lidar, and an infrared sensor; these were supported by in situ measurements of aircraft and environmental parameters and by ground-based Doppler radars. The basic problem addressed was the airborne detection and measurement of meteorologically-induced wind shear sufficiently ahead of the aircraft to allow avoidance. If the remote measurements of the shear and its associated radar reflectivity did not exceed set limits, the airplane then continued through the wind shear so that in situ measurements could be made for comparison. Initial detection and vectoring to the wind shear was normally given from a ground-based Doppler weather radar and most of the wind shear events were due to microbursts, both wet and dry. This paper considers the problems of sampling the wind shear event, time and space registration among the various sensors, coordination of the various sensors' beams and sampling volumes, and also various techniques for portraying the data, both for research and for presentation. Examples are given based on data from the 1991 and 1992 NASA/FAA wind shear flights, and the results and conclusions are generalized to other flight experiments involving multi-sensor electromagnetic data sets.
Delnore, V. E.↗
Advanced X-ray Astrophysics Facility (AXAF) science instruments
The overall AXAF program is summarized, with particular emphasis given to its science instruments. The science objectives established for AXAF are to determine the nature of celestial objects, from normal stars to quasars, to elucidate the nature of the physical processes which take place in and between astronomical objects, and to shed light on the history and evolution of the universe. Attention is given to the AXAF CCD imaging spectrometer, which is to provide spectrally and temporally resolved imaging, or, in conjunction with transmission grating, high-resolution dispersed spectral images of celestial sources. A high-resolution camera, an X-ray spectrometer, and the Bragg Crystal Spectrometer are also discussed.
Winkler, Carl E.↗
Comparison of icing cloud instruments for 1982-1983 icing season flight program
A number of modern and old style liquid water content (LWC) and droplet sizing instruments were mounted on a DeHavilland DHC-6 Twin Otter and operated in natural icing clouds in order to determine their comparative operating characteristics and their limitations over a broad range of conditions. The evaluation period occurred during the 1982-1983 icing season from January to March 1983. Time histories of all instrument outputs were plotted and analyzed to assess instrument repeatability and reliability. Scatter plots were also generated for comparison of instruments. The measured LWC from four instruments differed by as much as 20 percent. The measured droplet size from two instruments differed by an average of three microns. The overall effort demonstrated the need for additional data, and for some means of calibrating these instruments to known standards.
Ide, R. F.↗
Comparison of icing cloud instruments for 1982-1983 icing season flight program
A number of modern and old style liquid water content (LWC) and droplet sizing instruments were mounted on a DeHavilland DHC-6 Twin Otter and operated in natural icing clouds in order to determine their comparative operating characteristics and their limitations over a broad range of conditions. The evaluation period occurred during the 1982-1983 icing season from January to March 1983. Time histories of all instrument outputs were plotted and analyzed to assess instrument repeatability and reliability. Scatter plots were also generated for comparison of instruments. The measured LWC from four instruments differed by as much as 20 percent. The measured droplet size from two instruments differed by an average of three microns. The overall effort demonstrated the need for additional data, and for some means of calibrating these instruments to known standards.
Ide, R. F.↗